Filter/sanitizer

ABSTRACT

A filter/sanitizer has a filter housing, provided with a fluid inlet and a fluid outlet, a filter cartridge with a hollow interior, located within the filter housing, and a sanitizer cartridge, with a hollow core, positioned within the hollow interior of the filter cartridge. In a preferred embodiment, the sanitizer cartridge is constructed with an outer fluid-permeable member and an inner fluid-permeable member, the outer and inner members substantially enveloping a space therebetween, with the space containing a sanitizing media bed. In operation, as fluid enters the filter housing through the fluid inlet, substantially the full flow of fluid passes through the filter cartridge, through the sanitizer cartridge and around the sanitizing media contained within the bed, into the hollow core of the sanitizer cartridge, and out of the filter housing through the fluid outlet.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a §111(a) application relating to U.S. application Ser. No.60/036,970 filed Jan. 29, 1997.

FIELD OF THE INVENTION

The present invention relates to a device and method for filtering andchemical treatment of fluid within a cartridge-type filter.

BACKGROUND OF THE INVENTION

Cartridge-type filters for swimming pools, hot tubs, spas and the likearc well known in the art. Chemical treatment of pool water withsanitizing media such as bactericides, germicides or algaecides is alsoknown in the art. Combinations of cartridge-type filters and chemicaltreatment are limited in the art.

U.S. Pat. No. 4,780,197 combines a cartridge filter with a chlorinationmodule, but only a partial flow is directly in contact with the chemicaltreatment media. Even the insertion of a "tea bag" type apparatus filledwith sanitizing media, as disclosed in U.S. Pat. No. 4,416,854, into theinterior of a cartridge-type filter would not insure contact of the fullflow through the filter with the sanitizing media. A need exists for acombination of a cartridge-type filter and sanitizing treatment, wherebythe full system flow through the filter is directly in contact with thesanitizing media.

SUMMARY OF THE INVENTION

A cartridge-type filter is combined with a sanitizer cartridge (i.e., acanister) in a filter/sanitizer to both filter and chemically treat thefull flow of water through the apparatus. The sanitizer cartridge may beadapted to a wide range of conventional cartridge-type filters and awide range of sanitizing media, such as bactericides, germicides andalgaecides, as well as an equally wide range of water treatment media.

A sanitizer cartridge includes an outer perforated tube and an innerperforated tube suspended between an end cap and an outlet fitting. Theannular space between the inner and outer perforated tubes is filledwith sanitizing media. The sanitizer cartridge is positioned within thehollow center of a conventional filter cartridge in a cartridge-typefilter such that the outlet fitting is removably and sealingly connectedto the filter outlet.

Substantially the full flow through the filter cartridge flows directlythrough the sanitizing media in the sanitizer cartridge. Therefore,virtually all the water is both filtered and sanitized by thefilter/sanitizer.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention, reference is madeto the following detailed description of an exemplary embodimentconsidered in conjunction with the accompanying drawings, in which:

FIG. 1 is a cross-sectional view of a first exemplary embodiment of afilter/sanitizer constructed in accordance with the present invention;

FIG. 2 is an exploded view of the filter/sanitizer shown in FIG. 1;

FIG. 3 is an elevation of the sanitizer cartridge end cap for thefilter/sanitizcr shown in FIG. 1;

FIG. 4 is an elevation of the sanitizer cartridge outlet fitting for thefilter/sanitizer shown in FIG. 1;

FIG. 5 is a bottom plan view of the sanitizer cartridge outlet fittingshown in FIG. 6;

FIG. 6 is a sectional view of the sanitizer cartridge outlet fittingtaken along section line A--A in FIG. 5;

FIG. 7 is a bottom perspective view of an alternate embodiment of thesanitizer cartridge outlet fitting for the filter/sanitizer shown inFIG. 1;

FIG. 8 is a top perspective view of the sanitizer cartridge outletfitting shown in FIG. 7;

FIG. 9 is a cross-sectional view of a second exemplary embodiment of afilter/sanitizer constructed in accordance with the present invention;

FIG. 10 is an exploded view of the filter/sanitizer shown in FIG. 9;

FIG. 11 is an elevation of the sanitizer cartridge end cap for thefilter/sanitizer shown in FIG. 9;

FIG. 12 is a bottom plan view of the sanitizer cartridge end cap shownin FIG. 11;

FIG. 13 is an elevation of the sanitizer cartridge outlet fitting forthe filter/sanitizer shown in FIG. 9;

FIG. 14 is a bottom plan view of the sanitizer cartridge outlet fittingshown in FIG. 13;

FIG. 15 is a cross-sectional view taken along section line A--A in FIG.14;

FIG. 16 is a side view of the sanitizer cartridge for thefilter/sanitizer shown in FIG. 9;

FIG. 17 is an elevation of the restraining tab for the filter/sanitizershown in FIG. 9; and

FIG. 18 is a top plan view of the restraining tab shown in FIG. 17.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIGS. 1 and 2, there is shown a cartridge-type fluidfilter/sanitizer 10 which includes a filter housing 12, a filtercartridge 14 and a sanitizer cartridge 16. Before discussing each indetail, it is noted that the filter housing 12 and the filter cartridge14 are from a commercially available Hayward model C-550 "EASY-CLEAR"above ground filter. However, it should be understood that the inventionis not limited to this particular equipment.

The filter housing 12 includes a filter body 18 and a filter head 20.The filter body 18 has an externally threaded, open, upper end 22 and afilter base 24. The filter base 24 includes a water inlet 26 and acentering post 28. The centering post 28 is integrally molded or gluedin the center of the filter base 24. The centering post 28 is amultifunctional part which supports, centers and seals the bottom of thefilter cartridge 14 within the filter body 18. The centering post 28 hasa cylindrical body 30 with a smaller diameter cylinder 31 with ahemispherical top 32, centered thereupon, forming an annular shoulder34. The annular shoulder 34 supports the bottom end of the filtercartridge 14. The hemispherical top 32 centers the filter cartridge 14and provides a close fit between the smaller diameter cylinder 31 of thecentering post 28 and the inner diameter of a soft urethane filtercartridge end cap (not shown in FIG. 1), thereby forming a watertightpiston seal. The upper end 22 of the filter body 18 has a series ofexternal threads 36 adapted to attach the filter head 20 in a manner tobe described hereinafter.

Referring still to FIGS. 1 and 2, the filter head 20 is attached to thefilter body 18 with a locking ring 38. The locking ring 38 has acircular groove 40 and a series of internal threads 42. The lower end ofthe filter head 20 has an annular flange 44 that fits into the groove 40in the locking ring 38. The internal threads 42 in the locking ring 38are adapted to threadedly engage the external threads 36 on the filterbody upper end 22, thereby forcing the filter head 20 down into thefilter body 18. An O-ring 46 is thereby compressed as a piston sealbetween the filter head 20 and the filter body 18 to provide afluid-tight seal. The locking ring 38 pulls up on the filter head 20when unscrewed, thereby breaking the seal between the filter head 20 andthe filter body 18.

The filter head 20 also includes a sealing tube 48, with a bottom 49,and an outlet tube 50. The bottom 49 of the sealing tube 48 includes asmaller diameter tube 49a and an annular shoulder 49b. When the filterhead 20 is forced down into the filter body 18, the bottom 49 of thesealing tube 48 is forced down into the top of the filter cartridge 14.The annular shoulder 49b of the sealing tube 48 presses the filtercartridge 14 into the centering post 28 in the filter base 24. Thefilter cartridge 14 forms watertight piston seals between the smallerdiameter tube 49a on the bottom 49 of the sealing tube 48 and the topinner diameter of an upper soft urethane filter cartridge end cap 57asee FIG. 2) and between the bottom inner diameter of lower soft urethanefilter cartridge end 57b (see FIG. 2) and the smaller diameter cylinder31 of the centering post 28. This delineates an outer chamber 51 on theinlet side of the filter cartridge 14 within the filter housing 12. Thefilter cartridge 14 is a standard Hayward design including a pleated,reinforced, polyester body 52 suspended between urethane end caps 57a,57b (see FIG. 2) and a tubular, molded, perforated plastic, center core53 around a hollow interior 54.

Located in the center of the filter head 20, within the sealing tube 48,is the outlet tube 50. The outlet tube 50 has a check valve 55positioned inside, approximately at the midpoint of the outlet tube 50.The check valve 55 allows water to flow in one direction only, i.e., outof the filter/sanitizer 10 through the outlet tube 50. The outlet tube50 also has an internal throat 56. The internal throat 56 of the outlettube 50 is sealingly and removably attached to the sanitizer cartridge16 so that substantially all of the water must flow through thesanitizer cartridge 16 before exiting through the outlet tube 50. Theremovable attachment of the sanitizer cartridge 16 to the filter head 20allows the filter head 20 and sanitizer cartridge 16 to be handled as aunit for ease of installation and removal.

The disposable sanitizer cartridge 16 includes an outer perforated tube58 and an inner perforated tube 60, preferably of plastic mesh, butalternatively of metallic mesh. The sanitizer cartridge 16 also includesan end cap 62 and an outlet fitting 64 of plastic, metal or any othersuitable material. The perforated tubes 58, 60 are suspended and fixedbetween the end cap 62 and the outlet fitting 64, forming an annularspace 66 between the outer perforated tube 58 and the inner perforatedtube 60. While the space 66 is shown as being annular, the space 66 canbe of any toroidal shape. The inside of the inner perforated tube 60 isa hollow core 67.

The sanitizer cartridge 16 contains a sanitizing media 68. Moreparticularly, the sanitizing media 68, typically in the form of pellets,tablets or a granular composition, is contained within the annular space66. The sanitizing media 68 is in a bed in the shape of the space 66. Inother words, if the space 66 is toroidal, the sanitizing media 68 willbe in a toroidially-shaped bed. The sanitizing media 68 may include anybactericidal, germicidal, algaecidal or other biocidal substancessuitable for the particular application. Silver-based bactericides orbiocides, which include such things as elemental silver coated orimpregnated carriers, divalent silver compositions and trivalent silvercompositions, are particularly effective for some water applications.Electrolytic metal compositions, including silver and copper, copper andzinc or any other suitable combination, may also be used. Chlorine basedcompositions may also be acceptable, as well as any suitable watertreatment media.

FIG. 3 is a detail of the end cap 62 of the sanitizer cartridge 16. Theend cap 62 includes a thin, solid circular base 70 with two concentric,solid tubes, namely an outer tube 72 and an inner tube 74, affixed toone side. The outer tube 72 has a smaller diameter than the base 70, andforms an annular shoulder 76 around the outside of the base 70. Theouter perforated tube 58 rests on the shoulder 76 and is fixed to thebase 70 and the outer tube 72 with epoxy or another suitable adhesive.The inner perforated tube 60 is fixed to the base 70 and the inside ofthe inner tube 74 with epoxy or another suitable adhesive. The end cap62 effectively seals one end of the sanitizer cartridge 16 so that fluidflow into the hollow core 67 cannot bypass the sanitizing media 68 inthe annular space 66.

The other end of the sanitizer cartridge 16 has an outlet fitting 64.The outlet fitting 64 seals the annular space 66 containing thesanitizing media 68 and sealingly attaches the sanitizer cartridge 16 tothe internal throat 56 of the outlet tube 50 in the filter head 20. Thisarrangement causes substantially all of the fluid flow to pass throughthe sanitizer cartridge 16 before exiting through the outlet tube 50.With particular reference to FIGS. 4-6, this configuration of the outletfitting 64 allows retrofitting the sanitizer cartridge 16 to the Haywardmodel C-550 "EASY-CLEAR" above ground filter. Alternatively, the outletfitting 64 may have internal threads arranged to engage external threadson the throat 56 of the outlet tube 50.

Referring to FIGS. 4-6, the outlet fitting 64 includes an annularcentral partition 78 with a centered circular opening 80 that allowswater to pass completely through the outlet fitting 64. The outletfitting 64 also includes two concentric, solid tubes, i.e., an outertube 82 and an inner tube 84, affixed to one side in the sameconfiguration as the end cap 62 of the sanitizer cartridge 16. The outertube 82 has a smaller diameter than the central partition 78, and formsan annular shoulder 86 around the outside of the central partition 78.The outer perforated tube 58 rests on the shoulder 86 and is fixed tothe central partition 78 and the outer tube 82 with epoxy or anothersuitable adhesive. The inner perforated tube 60 is fixed to the centralpartition 78 and the inside of the inner tube 84 of the centralpartition 78 with epoxy or another suitable adhesive. The connections ofthe outlet fitting 64 and the end cap 62 to the perforated tubes 58, 60seal the sanitizing media 68 within the annular space 66 between theperforated tubes 58, 60, completing the sanitizer cartridge 16.

Still referring to FIGS. 4-6, the portion of the outlet fitting 64 belowthe central partition 78 connects to the throat 56 of the outlet tube50. Affixed below the central partition 78 is a concentrically centeredtube structure 88 with three sections. The first section 90 is tubular.The second section 92 is a tapered annular ring designed to mate withthe interior of the filter head 20. The third section 94 is also tubularwith an inner diameter greater than the inner diameter of the firstsection 90. The second section 92 has two inner diameters the same asthe inner diameters of the adjacent sections, forming an annularinterior shoulder 96 at their junction.

The throat 56 of the outlet tube 50 slidingly seats against the interiorshoulder 96. Three slots 98 are cut and positioned equidistantly aroundthe tube structure 88. These slots 98 align with structures in the formof fingers, ribs or the like (not shown) in the filter head 20. Thenumber and orientation of these slots 98 or other openings orprotrusions and the corresponding structures in the filter head 20 canbe varied to uniquely fit a particular sanitizer cartridge 16 to auniquely corresponding filter/sanitizer 10.

With reference to FIG. 6, an aperture 100 is provided in the secondsection 92 of the tubular structure 88. A self-threading screw (notshown) with a length slightly longer than the depth of the aperture 100is threadedly inserted into the aperture 100. Once the throat 56 of theoutlet tube 50 slidingly seats against the interior shoulder 96, thescrew is tightened so that it grippingly penetrates the outer surface ofthe throat 56, thereby holding the sanitizer cartridge 16 in the filterhead 20.

In operation, the flow path for the full system flow, as indicated inFIG. 1 by the flow arrows 102, begins at the water inlet 26 into theouter chamber 51 of the filter/sanitizer 10. The cylindrical filtercartridge 14 with the hollow interior 54 is sealingly positioned aroundthe smaller diameter tube 49a on the bottom 49 of the sealing tube 48 inthe filter head 20 and the smaller diameter cylinder 31 of the centeringpost 28 in the filter base 24 such that all of the water flows from theouter chamber 51 through the filter cartridge 14 into its hollowinterior 54 towards the outlet tube 50.

The cylindrical sanitizer cartridge 16 with the cylindrical hollow core67, sealed at one end by the end cap 62, is positioned within the hollowinterior 54 of the filter cartridge 14. A clearance between the centercore 53 of the filter cartridge 14 and the outer perforated tube 58 ofthe sanitizer cartridge 16, sufficient for water to circulate, ismaintained. By maximizing the diameters of the outer perforated tube 58and the inner perforated tube 60, the inlet and outlet areas of thesanitizer cartridge 16 are also maximized. This maximization of areas,in conjunction with minimizing the thickness of the layer of sanitizingmedia 68, enables substantially the full flow of the water through thefilter cartridge 14 to pass through the sanitizer cartridge 16 withoutan excessive pressure drop.

The outlet fitting 64 of the sanitizer cartridge 16 is removably andsealingly attached to the internal throat 56 of the outlet tube 50.Substantially all of the water flows through the sanitizing media 68 inthe annular space 66 in the sanitizer cartridge 16, then into itscylindrical hollow core 67 and, finally, out of the filter/sanitizer 10through the outlet tube 50. Thus, the full flow of water through thefilter/sanitizer 10 is both filtered by the filter cartridge 14 anddisinfected by the sanitizing media 68 within the sanitizer cartridge16.

FIGS. 7 and 8 show an alternative embodiment of an outlet fitting 102for the sanitizer cartridge 16. The outlet fitting 102 includes anannular central partition 103a with a centered circular opening 103bthat allows water to pass completely through the outlet fitting 102. Theoutlet fitting 102 also includes three concentric, solid tubes, i.e., anouter tube 104a, an inner tube 104b, and a flow-through tube 104c. Theouter tube 104a surrounds the periphery of the central partition 103aand extends above and below the central partition 103a. The inner tube104b has a smaller diameter than the outer tube 104a and extends belowthe central partition 103a. An outer space 105a is formed in between theouter tube 104a and the inner tube 104b. The flow-through tube 104c hasa smaller diameter than the inner tube 104b and extends below thecentral partition 103a, slightly beyond the inner tube 104b and feedsdirectly into the circular opening 103b. An inner space 105b is formedin between the inner tube 104b and the flow-through tube 104c.

The outer perforated tube 58 rests against the bottom of the centralpartition 103a and in the outer space 105a, which is only large enoughto accommodate the width of the outer perforated tube 58, which is thenfixed in place in the outer space 105a with epoxy or another suitableadhesive. The inner perforated tube 60 rests against the bottom of thecentral partition 103a and in the inner space 105b, which is only largeenough to accommodate the width of the inner perforated tube 60, whichis then fixed in place in the inner space 105b with epoxy or anothersuitable adhesive.

Three slots 106 are cut in and positioned equidistantly around theportion of the outer tube 104a that extends above the central partition103a. These slots 106 align with structures in the form of fingers,ribs, or the like (not shown) in the filter head 20. Three projections107 are positioned above the central partition 103a, adjacent to aninner surface 108a of the outer tube 104a, and are spaced equidistantlybetween the three slots 106. These projections 107 are used to centerthe outlet fitting 102 in the filter head 20.

An aperture 109 is provided in an exterior surface 108b of the outertube 104a. A self-threading screw (not shown) with a length slightlylonger than the depth of the aperture 109 is threadedly inserted intothe aperture 109. Once the throat 56 of the outlet tube 50 slidinglyseats in between the three projections 107, the screw is tightened sothat it grippingly penetrates the structure (not shown) depending fromthe filter head 20 that is positioned in the slot 106 that is adjacentto the aperture 109.

There are many alternate embodiments (not shown) of the invention thatallow all or substantially all the flow through a standard, hollow,cylindrical, filter cartridge 14 to flow through a sanitizer cartridge16. In alternate embodiments (not shown), the sanitizer cartridge 16 maybe refillable in contrast to disposable.

In another alternate embodiment (not shown), the sanitizer cartridge 16may be combined with the filter cartridge 14 to form a single, unitaryfilter/sanitizer element. In this embodiment, the outer perforated tube58 of the sanitizer cartridge 16 would replace the center core 53 of thefilter cartridge 14.

In yet another alternate embodiment (not shown), a universal sanitizercartridge can be configured. A universal sanitizer cartridge includesall of the features of the sanitizer cartridge 16 illustrated anddescribed in FIGS. 1-6 except for the outlet fitting 64. The outletfitting for the universal sanitizer cartridge would be like the outletfitting 64 shown in FIG. 4, but without the tubular structure 88. A thinannular gasket (not shown), with an outer diameter larger than thediameter of the scaling tube 48 and less than the outer diameter of thefilter cartridge 14 and an inner diameter equal to the diameter of thecircular opening 80 in the central partition 78 of the outlet fitting64, replaces the tubular structure 88. The annular gasket would beattached to the central partition 78 with any suitable adhesive. Theuniversal sanitizer cartridge would be placed into the hollow interior54 of the filter cartridge 14 so that the annular gasket attached to thecentral partition 78 of the outlet fitting 64 would extend substantiallyover the top of the filter cartridge 14. When the filter head 20 isforced down by the locking ring 38, the annular gasket on the outletfitting would be sealingly compressed between bottom 49 of the sealingtube 48 and the filter cartridge 14. The full flow of water would passfrom the outer chamber 51 through the filter cartridge 14 into itshollow interior 54, then through the sanitizing media 68 into thecylindrical hollow core 67 of the universal sanitizer cartridge and,finally, out through the circular opening 80 in the modified outletfitting 64 and the outlet tube 50.

Referring to FIGS. 9 and 10, in an alternate embodiment of theinvention, there is shown a cartridge-type fluid filter/sanitizer 110which includes a filter housing 112, a filter cartridge 114 and asanitizer cartridge 116. Before discussing each in detail, it is notedthat the filter housing 112 and the filter cartridge 114 are from acommercially available Hayward model C-1200 "STAR-CLEAR PLUS" in-groundfilter. However, it should be understood that the invention is notlimited to this particular equipment.

The filter housing 112 includes a filter body 118 and a filter head 120.The filter body 118 has an open, upper end 122 and a filter base 124.The filter base 124 includes a water inlet 126, an outlet tube 128, witha top 129, and a water outlet 130. The outlet tube 128 is integrallymolded in the center of the filter base 124. The outlet tube 128 is amultifunctional part which supports, centers and seals the bottom of thefilter cartridge 114 within the filter body 118. The outlet tube 128also supports, centers and seals the sanitizer cartridge 116 within thefilter body 118. The top 129 of the outlet tube 128 includes a smallerdiameter tube 129a and an annular shoulder 129b. The water outlet 130,which is in the form of a horizontal tube, is connected to the outlettube 128. An outlet chamber 132 is formed by the hollow interiors of theoutlet tube 128 and the water outlet 130. The upper end 122 of thefilter body 118 has an annular shoulder 134 adapted to support thefilter head 120 in a manner to be described hereinafter.

Referring still to FIGS. 9 and 10, the filter head 120 has a domed top136 and a cylindrical lower end 138 with an annular flange 140. Thefilter head 120 is attached to the filter body 118 with a locking knob142 and a threaded rod 144. The threaded rod 144 is threadedly attachedto the filter base 124 with a suitable threaded attachment 146. Thelocking knob 142 has a series of internal threads 148. The internalthreads 148 in the locking knob 142 are adapted to threadedly engage thethreaded rod 144, thereby forcing the filter head 120 down into thefilter body 118. An O-ring 150 is thereby compressed as a piston sealbetween the filter head 120 and the filter body 118 to provide afluid-tight seal.

The filter head 120 also includes a sealing tube 152 with a bottom 153.The bottom 153 of the sealing tube 152 includes a smaller diameter tube153a and an annular shoulder 153b. When the filter head 120 is forceddown into the filter body 118, the bottom 153 of the sealing tube 152 isforced down into the top of the filter cartridge 114. The annularshoulder 153b of the sealing tube 152 presses the filter cartridge 114into the outlet tube 128 in the filter base 124. The filter cartridge114 forms watertight piston seals between the smaller diameter tube 153aon the bottom 153 of the sealing tube 152 and the top inner diameter ofan upper soft urethane filter cartridge end cap 161a (see FIG. 10) andbetween the bottom inner diameter of lower soft urethane filtercartridge end cap 181a (see FIG. 10) and the smaller diameter tube 129aon the top 129 of the outlet tube 128. This delineates an outer chamber154 on the inlet side of the filter cartridge 114 within the filterhousing 112. The filter cartridge 114 is a standard Hayward designincluding a pleated, reinforced, polyester body 156 suspended betweenurethane end caps 161a, 161b (see FIG. 10) and a tubular, molded,perforated plastic, center core 158 around a hollow interior 160.

The disposable sanitizer cartridge 116 is positioned within the hollowinterior 160 of the filter cartridge 114 (see FIG. 10). The sanitizercartridge 116 includes an outer perforated tube 162 and an innerperforated tube 164, preferably of plastic mesh, but alternatively ofmetallic mesh. The sanitizer cartridge 116 also includes an end cap 166and an outlet fitting 168 of plastic, metal or any other suitablematerial. The perforated tubes 162, 164 are suspended and fixed betweenthe end cap 166 and the outlet fitting 168, forming an annular space 170between the outer perforated tube 162 and the inner perforated tube 164.The inside of the inner perforated tube 164 is a hollow core 172.

The sanitizer cartridge 116 contains a sanitizing media 174. Thesanitizing media 174, typically in the form of pellets, tablets or agranular composition, is contained within the annular space 170. Thesanitizing media 174 may include any bactericidal, germnicidal,algaecidal or other biocidal substances suitable for the particularapplication. Silver-based bactericides or biocides, which include suchthings as elemental silver coated or impregnated carriers, divalentsilver compositions and trivalent silver compositions, are particularlyeffective for some water applications. Electrolytic metal compositions,including silver and copper, copper and zinc or any other suitablecombination, may also be used. Chlorine based compositions may also beacceptable, as well as any suitable water treatment media.

Referring to FIGS. 11 and 12, end cap 166 of the sanitizer cartridge 116includes an annular partition 176 with a concentric, solid tube 178affixed to one side. The tube 178 has an outer diameter less than theouter diameter of the partition 176, and forms an outer annular shoulder180 around the outside of the partition 176. The outer perforated tube162 rests on the outer annular shoulder 180 and is fixed to thepartition 176 and the outside of tube 178 with epoxy or another suitableadhesive. The tube 178 has an inner diameter greater than the innerdiameter of the partition 176 and forms an inner annular shoulder 182around the inside of the partition 176. The inner perforated tube 164rests on the inner annular shoulder 182 and is fixed to the partition176 and the inside of the tube 178 with epoxy or another suitableadhesive.

Still referring to FIGS. 11 and 12, the portion of the end cap 166 abovethe partition 176 includes a hollow frustum 184 with a small circularopening 186 in the top of the frustum 184 and a large circular opening188 in the bottom of the frustum 184. The circular openings 186, 188allow the threaded rod 144 to pass through the end cap 166. The diameterof the opening 186 is only slightly larger than the diameter of thethreaded rod 144 to minimize fluid bypass from the hollow interior 160of the filter cartridge 114 to the hollow core 172 of the sanitizercartridge 116 through the circular openings 186,188. An external flange189 is positioned just below the top of the hollow frustum 184. Theflange 189 functions as a handle to lift the sanitizer cartridge 116.

The other end of the sanitizer cartridge 116 has a tubular outletfitting 168. The outlet fitting 168 seals the annular space 170containing the sanitizing media 174 and sealingly seats the sanitizercartridge 116 in the outlet tube 128 in the filter base 124. Thisarrangement causes substantially all of the fluid flow to pass throughthe sanitizer cartridge 116 before exiting through the outlet tube 128.With particular reference to FIGS. 13-15, this configuration of theoutlet fitting 168 allows retrofitting the sanitizer cartridge 116 tothe Hayward model C-1200 "STAR-CLEAR PLUS" in-ground filter.

Referring to FIGS. 13-15, the outlet fitting 168 includes threesections. The top section 190 is tubular with an internal, annularshoulder 192. The middle section 194 is a tubular frustum with a largerdiameter bottom. The bottom section 196, which is also tubular, includesthree annular shoulders; namely, an external, upper shoulder 198, anexternal, lower shoulder 200 and an internal shoulder 202. A chamfer 204is included around the lower end of the bottom section 196.

Twelve identical notches 206 are symmetrically spaced about the lowerend of the bottom section 196. Also attached to the lower end of thebottom section 196 are four identical tapered fingers 208. The taperedfingers 208 are spaced at 90° intervals, equidistantly between adjacentnotches 206 (see FIG. 14). These notches 206 align with structures inthe form of fingers, ribs or the like (not shown) in the filter base124. The number and orientation of these notches 206 or other openingsor protrusions and the corresponding structures in the filter base 124can be varied to uniquely fit a particular sanitizer cartridge 116 to auniquely corresponding filter/sanitizer 110.

Referring now to FIG. 13, the inner perforated tube 164 slides into thetop section 190 of the outlet fitting 168, rests upon the annularshoulder 192 and is fixed inside the top section 190 with epoxy oranother suitable adhesive. The outer perforated tube 162 slides aroundthe top of the bottom section 196 and rests on the external, uppershoulder 198. The outer perforated tube 162 is also fixed to the bottomsection 196 with epoxy or another suitable adhesive. The connections ofthe outlet fitting 168 and the end cap 166 to the perforated tubes 162,164 seal the sanitizing media 174 within the annular space 170 betweenthe perforated tubes 162, 164 completing the sanitizer cartridge 116(see FIG. 16). When the sanitizer cartridge 116 is positioned inside thehollow interior 160 of the filter cartridge 114 within the filter body118, the external lower shoulder 200 of the outlet fitting 168 sealinglyrests on the smaller diameter tube 129a at the top 129 of the outlettube 128.

Referring to FIGS. 17 and 18, a restraining tab 210 has a large diameteraperture 212 and small diameter aperture 214. The large diameteraperture 212 is placed over the threaded rod 144. The small diameteraperture 214 is placed over the lower end of an air hose (not shown).The restraining tab 210 is positioned as near to the bottom of theoutlet tube 128 as possible. The top end of the air hose (not shown) islocated in the hollow frustum 184 of the end cap 166 of the sanitizercartridge 116. The purpose of the air hose (not shown) is to prevent theaccumulation of air in the filter head 120 during operation of thefilter/sanitizer 110.

In operation, the flow through the filter/sanitizer 110, indicated inFIG. 9 by the flow arrows 216, begins at the water inlet 126 into theouter chamber 154. The cylindrical filter cartridge 114 with the hollowinterior 160 is sealingly positioned around the smaller diameter tube153a on the bottom 153 of the sealing tube 152 in the filter head 120and the smaller diameter tube 129a on the top 129 of the outlet tube 128in the filter base 124 such that all of the water flows from the outerchamber 154 through the filter cartridge 114 into its hollow interior160 towards the water outlet 130.

The cylindrical sanitizer cartridge 116 is positioned within the hollowinterior 160 of the filter cartridge 114. The threaded rod 144 passesthrough the outlet fitting 168, hollow core 172 and the small circularopening 186 in the top of the end cap 166, centering the sanitizercartridge 116 within the filter body 118. A clearance between the centercore 158 of the filter cartridge 114 and the outer perforated tube 162of the sanitizer cartridge 116, sufficient for water to circulate, is tomaintained. By maximizing the diameters of the outer perforated tube 162and the inner perforated tube 164, the inlet and outlet areas of thesanitizer cartridge 116 are also maximized. This maximization of areas,in conjunction with minimizing the thickness of the layer of sanitizingmedia 174, enables substantially the full flow of the water through thefilter cartridge 114 to pass through the sanitizer cartridge 116 withoutan excessive pressure drop.

The outlet fitting 168 of the sanitizer cartridge 116 is removably andsealingly positioned in the outlet tube 128. Substantially all of thewater flows through the sanitizing media 174 in the annular space 170within the sanitizer cartridge 116, then into its cylindrical hollowcore 172 and, finally, out of the filter/sanitizer 110 through theoutlet tube 128 and the water outlet 130. Thus, the full flow of waterthrough the filter/sanitizer 110 is both filtered by the filtercartridge 114 and disinfected by the sanitizing media 174 within thesanitizer cartridge 116.

There are many alternate embodiments (not shown) of the invention thatallow all or substantially all the flow through a standard, hollow,cylindrical, filter cartridge 114 to flow through a sanitizer cartridge116. In alternate embodiments (not shown), the sanitizer cartridge maybe refillable in contrast to disposable.

In another alternate embodiment (not shown), the sanitizer cartridge 116may be combined with the filter cartridge 114 to form a single, unitaryfilter/sanitizer element. In this embodiment, the outer perforated tube162 of the sanitizer cartridge 116 would replace the center core 158 ofthe filter cartridge 114.

It should be noted that the embodiments described herein are merelyexemplary and that a person skilled in the art may make many variationsand modifications without departing from the spirit and scope of theinvention. For instance, the embodiments disclosed may be adapted forany water treatment application with any suitable water treatment media.In addition, the present invention can be used to filter and chemicallytreat liquids other than water, as well as gaseous fluids. All suchvariations and modifications are intended to be included within thescope of the invention as defined in the appended claims.

I claim:
 1. A filter/sanitizer, comprising:a filter housing, with afluid inlet and a fluid outlet; a filter cartridge having a hollowinterior, said filter cartridge located within said filter housing; anda sanitizer cartridge having an outer fluid-permeable member and aninner fluid-permeable member, said outer fluid-permeable member and saidinner fluid-permeable member substantially enveloping a spacetherebetween which contains a sanitizing media, saidinnerfluid-permeable member bounding a hollow core, said sanitizercartridge being positioned substantially within said hollow interior ofsaid filter cartridge such that as fluid flows into said filter housingthrough said fluid inlet, substantially the full flow of the fluidpasses through said filter cartridge, through said sanitizer cartridgeand around said sanitizing media, and into said hollow core beforeexiting said filter housing through said fluid outlet, said sanitizercartridge also including an end cap having an annular partition with asolid concentric tube affixed to one side thereof, said concentric tubehaving an outer diameter smaller than an outer diameter of said annularpartition, thereby forming an outer annular shoulder around an outeredge of said annular partition, said concentric tube having an innerdiameter larger than an inner diameter of said annular partition,thereby forming an inner annular shoulder around an inner edge of saidannular partition, said outer fluid-permeable member resting on saidouter annular shoulder and being fixedly attached to said annularpartition and to an outer surface of said concentric tube, said innerfluid-permeable member resting on said inner annular shoulder and beingfixedly attached to said annular partition and to an inner surface ofsaid concentric tube, and a hollow frustum attached to an opposite sideof said annular partition, thereby closing said end cap and sealing oneend of said sanitizer cartridge.
 2. A filter/sanitizer according toclaim 1, wherein said filter/sanitizer filters and sanitizessubstantially all of the fluid passing therethrough.
 3. Afilter/sanitizer according to claim 1, wherein said outerfluid-permeable member is a perforated tube and said innerfluid-permeable member is a perforated tube.
 4. A filter/sanitizeraccording to claim 3, wherein said outer perforated tube and said innerperforated tube are plastic.
 5. A filter/sanitizer according to claim 3,wherein said outer perforated tube and said inner perforated tube aremetallic.
 6. A filter/sanitizer according to claim 1, wherein said fluidoutlet is located in a filter body and is provided with an outlet tubehaving a smaller diameter tube at its top, an outlet fitting of saidsanitizer cartridge sealingly engaging said outlet tube.
 7. Afilter/sanitizer according to claim 6, wherein said outlet fittingcomprises a tubular top section with an internal annular shoulder and atubular frustum middle section which widens into a tubular bottomsection, said bottom section being provided with an external uppershoulder and an external lower shoulder, said outer fluid-permeablemember being slidable around said tubular bottom section, resting onsaid external upper shoulder, and being fixedly attached to said tubularbottom section, said inner fluid-permeable member being slidable intosaid tubular top section, resting on said internal annular shoulder, andbeing fixedly attached inside said tubular top section, said externallower shoulder sealingly resting on said smaller diameter tube of saidoutlet tube, thereby providing a fluid outlet flow pathway from saidhollow core of said sanitizer cartridge through said outlet fitting,into said outlet tube, and out of said filter housing through said fluidoutlet.
 8. A filter/sanitizer, comprising:a filter housing, with a fluidinlet and a fluid outlet; a filter cartridge having a hollow interior,said filter cartridge located within said filter housing; and asanitizer cartridge having an outer fluid-permeable member and an innerfluid-permeable member, said outer fluid-permeable member and said innerfluid-permeable member substantially enveloping a space therebetweenwhich contains a sanitizing media, said innerfluid-permeable memberbounding a hollow core, said sanitizer cartridge being positionedsubstantially within said hollow interior of said filter cartridge suchthat as fluid flows into said filter housing through said fluid inlet,substantially the full flow of the fluid passes through said filtercartridge, through said sanitizer cartridge and around said sanitizingmedia, and into said hollow core before exiting said filter housingthrough said fluid outlet, said sanitizer cartridge also including anend cap having an annular partition with a solid concentric tube affixedto one side thereof, said concentric tube having an outer surface and aninner surface, said outer fluid-permeable member being fixedly attachedto said annular partition and to said outer surface of said concentrictube, said inner fluid-permeable member being fixedly attached to saidannular partition and to said inner surface of said concentric tube, anda hollow frustum attached to an opposite side of said annular partition,thereby closing said end cap and sealing one end of said sanitizercartridge.
 9. A filter/sanitizer, comprising:a filter housing, with afluid inlet and a fluid outlet including an outlet tube having a smallerdiameter tube at its top; a filter cartridge having a hollow interior,said filter cartridge located within said filter housing; and asanitizer cartridge having an outer fluid-permeable member and an innerfluid-permeable member, said outer fluid-permeable member and said innerfluid-permeable member substantially enveloping a space therebetweenwhich contains a sanitizing media, said inner fluid-permeable memberbounding a hollow core, said sanitizer cartridge being positionedsubstantially within said hollow interior of said filter cartridge suchthat as fluid flows into said filter housing through said fluid inlet,substantially the full flow of the fluid passes through said filtercartridge, through said sanitizer cartridge and around said sanitizingmedia, and into said hollow core before exiting said filter housingthrough said fluid outlet, said sanitizer cartridge also including anoutlet fitting including a tubular top section and a tubular frustummiddle section which widens into a tubular bottom section, said bottomsection being provided with an external lower shoulder, said outerfluid-permeable member sliding around and being fixedly attached to saidbottom section, said inner fluid-permeable member sliding into and beingfixedly attached inside said top section, said external lower shouldersealingly resting on said smaller diameter tube of said outlet tube,thereby providing a fluid outlet flow pathway from said hollow core ofsaid sanitizer cartridge through said outlet fitting, into said outlettube, and out of said filter housing through said fluid outlet.